This invention relates to guide wires which are steerable by reason of shape memory materials used in their construction.
A guide wire is a medical device that is typically formed of a long, flexible metal wire coiled or uncoiled, and having one or more components. They are generally used to gain access to a body structure or location by inserting it into the body and advancing it to the desired location. The guide wire can be used to probe, biopsy, penetrate, dilate or act as a vehicle for transporting an accompanying catheter to a given location.
It is, of course, desirable to provide a readily insertable guide wire that is also accurately steerable. Effective tip or body deflection of the wire, which provides the necessary steering capability, is important so that the guide wire can be quickly and accurately steered and guided through the desired path to the desired target structure or location within the body. In the past, guide wire designs have either lacked active steering capability, or they have incorporated mechanical steering designs which are large, awkward to use, and have limited steering characteristics. In this regard, typical guide wire constructions are shown in U.S. Pat. Nos. 4,619,274; 4,545,390; 4,538,622 and 3,528,406.
Quick, safe and effective steering of the guide wire is very important in many medical applications, especially in angioplasty procedures. For example, in percutaneous transluminal coronary angioplasty (PTCA) procedures, an inflatable balloon catheter is used to dilate narrow (stenotic) lesion sites within coronary arteries. A guide wire usually precedes an associated catheter by establishing passage through, and location of its distal tip at the site of the coronary artery narrowing, at which time the catheter is telescoped over the guide wire and advanced to the desired area. It will be appreciated that the anatomy of blood vessels in general, and especially so in coronary arteries, is very circuitous, or tortuous, with many side branches that complicate the successful passage of guide wires to their desired location. Thus, effective steering of the tip and/or body of the guide wire becomes very important for the quick, safe and accurate passage and placement of the guide wire preceding the transport and location of the PTCA catheter.
It is to be understood that the concept of a steerable guide wire is not limited to percutaneous transluminal coronary angioplasty (PTCA) procedures. Accurate steering capability is desirable in any guide wire used for any purpose such as, but not limited to, balloon and laser angioplasty, nephrostomy, angiography, electrode placement, etc.